Theoretical considerations on the appearance of sample and system peaks in ion chromatography with photometric detection

A general model is proposed for interpreting the appearance of sample and system peaks in ion-exchange chromatography with photometric detection. In this theory, a changed fraction of organic acid in the mobile phase resulting from the ion-exchange process with a sample ion migrates through the column from plate to plate in accordance with the ionic and partition equilibria. This perturbation of UV-detectable components yields the sample and system peaks. Simulation of this theory by computer accounts well for the sample peaks observed in real ion chromatography. An equation expressing the sample response—capacity factor relationship at low mobile phase pH was derived.